Apparatus, system and method for network monitoring

ABSTRACT

Systems, methods, and devices are disclosed for monitoring optical communications between a managed location and a remote location. In particular, an optical signal is transmitted over an optical fiber and passed-through a test device. A portion of the optical signal is filtered from the original optical signal and passed to a monitoring unit. The monitoring unit may instruct one or more switches in the test device to loop the optical signal back toward the managed location. Subsequently, testing and monitoring may be performed at the managed location. The device may provide a test output or may transmit the information to the managed location.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application claiming priorityunder 35 U.S.C. §120 to co-pending utility application Ser. No.13/590,922 titled “Apparatus, System and Method for Network Monitoring”,filed on Aug. 21, 2012, which claims priority to provisionalapplications 61/561,641 titled “Systems and Methods for NetworkMonitoring,” filed on Nov. 18, 2011, 61/670,531 titled “Apparatus,System and Method for Network Monitoring,” filed Jul. 11, 2012, and61/670,526 titled “Apparatus, System and Method for Network Monitoring,”filed Jul. 11, 2012, all of which are hereby incorporated by referenceherein.

TECHNICAL FIELD

Aspects of the present disclosure relate to optical communicationnetworks, and in particular, methods and systems for monitoring opticalsignals in an optical communication network.

BACKGROUND

Optical communication networks often require monitoring and testing ofthe various fiber links and/or optical pathways that make up the opticalnetwork to ensure the validity, continuity, and status of such fiberlinks and pathways. For example, optical links require monitoring todetect disconnections, physical breaks, and faults so that correctiveaction can be taken. It is often the case that service providers mustinstall expensive equipment, such as termination equipment, at acustomer's site to monitor its optical network links and fibers.Alternatively, optical network service providers may dispatch amaintenance crew to a customer's location for testing and monitoringpurposes, which is both expensive and time-consuming.

U.S. Pat. No. 7,778,554 describes a cost-effective way to monitoroptical network links. Generally speaking and referring to FIG. 1 of the'554 patent reproduced here as FIG. 1 (prior art), the technologydiscussed in the '554 patent involves over-coupling an amplitudemodulated signal onto a transmission line 1, such as on a transmissionfiber 3, emanating from a first end of the transmission line at atransmitter/receiver device 7. At a second end of the transmission link,the small amplitude modulated portion of the overall signal on thetransmission line is then returned to the first end of the transmissionline along a receive fiber 5. The second end of the transmission lineincludes two coupling elements (13,15) that collectively remove thesmall amplitude modulated signal from the transmit line and thensuperimpose the amplitude modulated signal on the receive line forreturn to the transmitter/receiver 7 at the first end of thetransmission link. A detector device 11 then compares the small signalto a threshold to determine if the received signal level is too low.

Notably, the solution set out in the '554 patent can only determine ifthere is an error in the entirety of the path to and from theoriginating end of the transmission line. Stated differently, becausethe signal is only monitored for an error at the originating end of thepath, the signal must traverse both the transmit and the receive pathsand there is not a way to isolated those paths. Hence, there is nomechanism whereby an error can be isolated to the transmit line or thereceive line. Moreover, there is no mechanism to determine the signalstrength at the receiving end and thus only of the transmit line. It iswith these observations in mind, among others, that various aspects ofthe present disclosure were conceived and developed.

SUMMARY

One aspect of the present disclosure involves an optical test deviceapparatus including at least one optical filter coupled with a firstoptical fiber. The first optical filter is configured to allow anoptical signal on the first optical fiber to pass from the first opticalfiber to a second optical fiber. The optical test device furtherincludes at least one monitoring device coupled with the at least oneoptical filter. The monitoring device is configured to receive a portionof the optical signal to test the optical signal. Finally, the opticaltest device includes a first switch in communication with the firstoptical fiber. The switch is configured to switch the optical signal onthe first optical fiber to a third optical fiber for loop-back testing.

In another aspect, the optical test device, or a system incorporatingthe same, includes an optical device to provide the signal to theoptical test device. The signal may include data that initiates a loopback test. Further, the monitoring device may be configured to detect apower level of the portion of the optical signal and compare thedetected power level of the portion of the optical signal with athreshold power level.

Aspects of the present disclosure may also involve a testing methodincluding the operations of receiving an optical signal at an opticaltest device, which may include at least one monitoring device and afirst switch. The method may further include receiving, at themonitoring device, a portion of the optical signal to test the opticalsignal, and altering the state of the optical test device from a firststate (e.g., pass through) to a second state (e.g., loop back) when asignal is detected at the optical device.

Yet another aspect of the present disclosure involves an optical systemincluding an optical test device. The optical test device includes afirst optical filter coupled with a first optical fiber. The firstoptical fiber carries a test signal on at least one wavelength carriedby the first optical fiber. The filter is configured to allow the testsignal to pass from the first optical fiber to a second optical filterof the optical test device. The second optical filter is configured toplace the test signal on a second optical fiber. The system furtherincludes a network device coupled with the second optical fiber. Thenetwork device includes a third filter configured to receive the testsignal if it is present on the second optical fiber, and determine acharacteristic of at least one of the first optical fiber or the secondoptical fiber.

Finally, aspects of the present disclosure also include a method oftesting an optical connection between devices. The method, in onepossible implementation, includes the operation of receiving, at aremote device, a test signal on a particular wavelength of a pluralityof wavelengths carried by a first optical fiber. The method furtherincludes returning the test signal on a second optical fiber where thetest signal is returned on the particular wavelength. Finally, themethod includes determining a characteristic of at least the firstoptical fiber or the second optical fiber at a second device.

These and other aspects of the present disclosure are discussed in moredetail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the presentdisclosure set forth herein will be apparent from the followingdescription of particular embodiments of those inventive concepts, asillustrated in the accompanying drawings. It should be noted that thedrawings are not necessarily to scale; however the emphasis instead isbeing placed on illustrating the principles of the inventive concepts.Also, in the drawings the like reference characters refer to the sameparts throughout the different views.

FIG. 1 (Prior Art) is an example of a conventional test device

FIG. 2 is a block diagram illustrating an optical test device in anoptical communication network, in accordance with an embodiment of thepresent disclosure.

FIG. 3A is block diagram illustrating an example of an optical testdevice, in accordance with an embodiment of the present disclosure.

FIG. 3B is another block diagram illustrating an example of an opticaltest device, in accordance with an embodiment of the present disclosure.

FIG. 4 is block diagram illustrating another example of an optical testdevice, in an optical communication network in accordance with anembodiment of the present disclosure.

FIG. 5A is a block diagram illustrating an example of a provider opticaltest device in an optical communication network, in accordance with anembodiment of the present disclosure.

FIG. 5B is another block diagram illustrating an example provideroptical test device, in accordance with an embodiment of the presentdisclosure.

FIG. 6 is a method diagram illustrating an example method for monitoringan optical network, in accordance with an embodiment of the presentdisclosure.

FIG. 7 is a block diagram of another example optical test device, inaccordance with an embodiment of the present disclosure.

FIG. 8 is another block diagram of an example optical test device.

DETAILED DESCRIPTION

The present disclosure describes methods and systems for monitoring andtesting optical connections and/or optical fibers in an opticalcommunication network. In various implementations, a cost-efficientoptical test device and system is described that enhances the ability totest and monitor optical network connections, optical signals, and/oroptical fiber links, among other capabilities. In one configuration, thedevice is discrete, cost effective, and may be employed and operatedlocally or remotely without the need for more costly and sophisticatedon-site equipment, or without the need for access to the customer'sequipment.

The use of optical technologies in communication networks is extensivebecause of their high speeds and the ability to transmit large amount ofdata. Generally speaking, an optical communication network involvesoptical fibers, such as thin flexible glass filaments, through whichdata can be transmit in the form of light, over long distances betweenvarious types of computing equipment, such as web servers, routers,telecommunication devices, voice over IP (VOIP) devices, processingdevices, and the like. By using techniques such as wavelength-divisionmultiplexing to modulate data on different wavelengths (colors) of lighton any given fiber it is possible to carry 40 or more different channelsof data on a fiber. Additionally, in contrast to copper or other metalcables, optic fibers can carry data at higher frequencies and overlonger distances with less attenuation and interference. As the use ofsuch networks become more ubiquitous, there arises a need to monitor andtest various fiber links and/or optical pathways that make up theoptical network to ensure the validity and continuity of the transmitteddata. Typically it is the responsibility of the optical networkproviders to ensure that data transmission is uninterrupted, or if anyfaults are detected to take appropriate corrective measures to resolveany of the data transmission related issues. Currently, most of themonitoring and testing is done by dispatching a maintenance crew to acustomer's location, which can be both expensive and time consuming.Thus there is a need for a more cost effective and time efficient methodfor performing these operations. In particular there is a need for amonitoring and testing the optical communication network without theneed for a sophisticated on site equipment or even without the need toaccess customer equipment.

Optical network service providers sell a variety of opticalcommunication services to business, enterprises, carriers, data hostcenters, and/or other customers. In order to provide such services tocustomers, an optical connection between the customer and the opticalnetwork is typically required. When such a network service provider isoperating a data network including high speed and high bandwidth opticalnetwork equipment and fibers, the optical connection to the customerprovides the customer with access to the network service provider'snetwork. Such a connection may be accomplished in a variety of ways. Forexample, a network service provider may provide access to the opticalnetwork by extending optic fibers to a customer and installingspecialized equipment on-site at the customer's location, such asoptical termination equipment. In another example, the service networkprovider may extend optical cable(s) directly into a customer'sproprietary equipment, such as an optical router, to provide opticalservices to the customer without the need of additional equipment.

While all such techniques may successfully allow access to the opticalnetwork, it is more cost-efficient to avoid installing equipment at acustomer location. In addition to the capital cost of the equipment,equipment located at customer location involves maintenance and servicecosts, equipment upgrade and software upgrade costs, as well as othercosts. Avoiding such costs would have many advantages. Moreover,installing equipment at a customer location could potentially become afailure point, which if eliminated would likely increase overallreliability of an optical connection.

However, when a network service provide connects an optical fiber to acustomer's proprietary equipment, it may be more difficult to testand/or monitor any optical links and/or fibers extended to the customerbecause customers often prohibit or restrict access to their equipment.For example, a customer may restrict access to its optical router thatis connected to a network service provider's optical fiber. Withoutaccess to the customer's equipment, the optical network service providercannot directly or efficiently monitor any optical signals sent to thecustomer. Aspects of the present disclosure, provide network serviceproviders the ability to test and monitor any optical connections,optical fibers, and/or optical links the network service provider hasprovided to a customer when no equipment has been installed at thecustomer's location.

The optical test device, in one possible implementation, is configuredto monitor the integrity of optical connections and fibers during normaloperation, and to enter a loop-back state, for additional testing aswell as to detect and isolate faults in the optical pathway betweenvarious possible network devices. More specifically, during normaloperation, the optical signal is allowed to directly pass through theoptical test device. On the other hand, in the loop-back state, theoptical signal is diverted back to the service provider device, in orderto conduct high additional testing on the optical signal and pathways.

FIG. 1 illustrates an example of an optical communication network 100 inwhich optical links, connections, and/or fiber optic cables providedbetween an optical network service provider's device 104 (or otherdevices) and a variety of possible customer devices 108 can be monitoredand tested by an optical test device 104 conforming to aspects of thepresent disclosure. An optical communication network is a data networkbuilt on or that otherwise includes fiber optics technology that allowselectronic devices, such as telephones and computers, to communicate bytransmitting data in the form of light over connected optical fibers andoptical links. An optical link generally describes a communication linkthat involves a single end-to-end optical circuit and typically includesone or more optical fibers that transmit and receive optical signals.While not illustrated, an optical network will typically includenumerous optical links and many different types of networking equipmentinvolved in the transmission, management, storage, and processing ofdata between companies.

According to one aspect of the current disclosure, the opticalcommunication network 100 includes an optical network service providerdevice 102 that represents a device and/or devices that provide Internetservices, telecommunication services, and/or other types of computingand communication services to customers through an optical communicationnetwork. For example, the network service provider device 102 may be aweb server that hosts and serves content accessible by a customercomputer connected to the Internet. As another example, the networkservice provider device 102 may be a network device providing high speedInternet access to customers. In yet another example, the networkservice provider device 102 may provide VOIP services to a customer.

In another aspect, the optical network service provider device 102 maybe any type of optical communication device capable of providing anoptical signal to a customer device 108. For example, the opticalnetwork service provider device 102 may include optical transmitters,receivers, transceivers, lasers, and/or couplers, and/or somecombination thereof. Other types of optical fiber and/or opticalcomponents may also be included in the optical network service providerdevice 102 and it is contemplated that any type of optical componentscapable of providing an optical signal, optical communications link,and/or optical communication to a customer device 108 may be included inthe optical network service provider device 102.

The optical network service provider device 102 sends an optical signalto the customer device 108 along a transmitting optical fiber 106, whichmay be a single optical fiber, or a multi-mode fiber. Additionally, thenetwork service provider device 102 receives optical signals from thecustomer device 108 along a receiving fiber 109, which also may be asingle optical fiber or multi-mode fiber. While FIG. 1 illustrates theoptical communication network 100 having a transmitting optical fiber(i.e. Tx fiber 106) and a receiving optical fiber (i.e. Rx fiber 109),the optical communication network depicted in FIG. 1 may also beimplemented using optical fibers capable of both transmitting andreceiving optical signals at the customer device 108 and the opticalnetwork service provider device 102.

The customer device 108 may be a processing device, a communicationdevice, or the like, such as a computer, a server computer, a networkdevice, and/or a mobile communication device that includes opticalcomponents, such as optical transmitters, optical receivers, and/oroptical couplers. The customer device 108 is operatively connected tothe Tx fiber 106 and the Rx fiber 109 and is capable of receiving andtransmitting optical signals using such fibers. For example, thecustomer device 108 may be a router, such as an optical router, capableof connecting to a fiber optic cable provided by the optical networkservice provider.

The optical test device 104 may be connected within any fiber optic linkbetween the optical network service provider device 102 and the customerdevice 108 to facilitate the testing and/or monitoring of opticalsignals, optical fibers, and/or other optical connections between anetwork service provider and a customer. In one possible arrangement,the optical test device 104 provides an interface between the opticalfibers connecting the customer and the service provider equipment.Hence, rather than being directly connected to the customer device 108,fibers from the network service provider device 102 are connected to theoptical test device 104. From the optical test device 104, which may beproximate to a customer device, one or more optical links are thenconnected to the customer device 108. In one possible arrangement, asshown in FIG. 1, transmit and receive fibers 106A and 109A from thenetwork service provider device 102 are connected with a first logicalside of the optical test device 104 and transmit and receive fibers 106Band 109B are connected with a second logical side of the optical testdevice 104. Alternatively, the optical device may be integrated withinthe provider device 102. Thus, while in one possible implementation, thedevice 104 is a stand alone device between the provider device and thecustomer device, the test device may be integrated in other equipment orotherwise provided at some point between along fiber paths betweendevices.

In a normal mode of operation, the optical signals from the networkservice provider device 102 pass directly through the optical testdevice 104 to the customer device 108, with only a basic monitoring ofthe integrity of the links being performed. Thus, when the optical testdevice is in the normal mode of operation, the transmit and receivefibers 106A and 109A are connected, through the test device, directlywith the transmit and receive fibers 106B and 109B, such that opticaltransmissions proceed unhindered and uninterrupted between the networkservice provider and the customer.

Additionally, the optical test device 104 may be configured to controlwhen the optical signals pass through the optical test device 104 orwhen the optical test device 104 facilitates monitoring and testing ofthe optical fiber links. For example, the optical test device 104 may beconfigured to change to a loop-back state during which optical signals,such as an optical signal received from the network service providerdevice 102, no longer pass through the optical device 104, but arerather looped back to the optical signal originating from the networkservice provider device 102 allowing testing and monitoring of anyfibers connecting the network service provider to the customer.

The process of “loop-back” discussed herein involves routing signals,such as optical signals, from an originating source along some path andback to the originating source without substantially modifying thesignal. In one possible implementation, the optical test device mayenter a loop-back state, upon detection of a control signal, where anoptical transmission path to the test device is switched or otherwiseconnected to an optical return path from the optical test device. Insuch a state, an optical signal on the transmission path is looped backon the return (or receive) path rather than be transmitted through theoptical device. For example, any optical signals originally transmittedfrom an upstream location, such as the network provider, to a downstreamlocation, such as a customer, will be looped back toward the upstreamlocation. Looping the optical signal back to the originating locationallows for various tests to be performed on the looped optical signal,such as verifying optical signal continuity, and allows those tests tobe performed from a remote location.

FIGS. 2A and 2B illustrate two possible implementations of an opticaltest device conforming to aspects of the present disclosure. The variouscomponents of the optical test device 104 transmit optical signals tothe customer device 108 as well as analyze optical signals to determinewhether the optical signals are valid or invalid. Additionally, thevarious components of the optical test device 104 may be used to changethe state of the optical test device 104 from its default pass throughstate (normal state) to a loop-back state, which allows a networkservice provider to conduct high-level tests of optical fibers, opticallinks, and/or the likes extending between the network service providerdevice 102 and the customer device 108.

According to one aspect of the current disclosure, the optical testdevice 104 may receive an optical signal from the network serviceprovider device 102 and transmit the optical signal to a filter 202.Alternatively, the optical device 104 may receive an optical signal fromthe customer device 108 and transmit the signal to a filter 204. Thefilters 202 and 204 are optical filters that receive optical signals.Generally, optical filters selectively transmit portions of light froman optical signal having certain properties, such as a particular rangeof wavelengths, while blocking the remainder. Optical filters may beused for multiplexing and demultiplexing, routing, attenuating,encoding, and/or decoding optical signals. The filters 202 and 204selectively pass or divert a portion of the optical signal, referred toas a test portion, to monitors 208 and/or 210 respectively, and allowthe remaining portion of the optical signal to continue transmittingthrough the optical test device 104. For example, the filter 202 mayfilter a percentage of the power of the optical signal (measured indecibels referenced to a milliwatt (dBm) and/or Watts) and pass it tothe monitor 208 while allowing the remainder of the optical signal tocontinue transmitting through the optical test device to the customerdevice 108. Similarly, filter 204 may direct a portion of an opticalsignal received on Rx Fiber 109B to the monitor 210 and allow theremainder of the optical signal to continue transmitting through theoptical test device to the service provider device 102.

In one embodiment, filters 202 and 204 may be an interference, adichromic, or other filter type that selectively pass a portion of theoptical signal to the monitor 208 and 210 respectively. An interferencefilter or dichroic filter is an optical filter that reflects one or morespectral bands or lines and transmits others (e.g. reflects a particularred wavelength of light and transmits a particular green wavelength oflight), while maintaining a nearly zero coefficient of absorption forall wavelengths of interest. An interference filter may be a high-pass,a low-pass, a bandpass, or a band-rejection filter that designatesdifferent wavelengths of light.

The monitors 208 and 210 represent computing and/or processing devicesthat include one or more processors and are configured to receiveoptical signals, optical data and/or other communications from thefilters 202 and 204. The monitors may include dedicated circuitcomponents, a programmable logic controller, and application specificintegrated circuit, a processor or other device. The monitors 208 and210 determine, in one specific implementation, whether the opticalsignal is valid or invalid, or whether there is a signal or no signal,and provide some indication thereof. For example, the monitor 208 and210 may determine whether a signal is present on the fiber. The transmitmonitor 208 measures the power level of the incoming input signal as apercentage of the expected power level, in one example. The transmitmonitor may include a light detector, optical sensor, photo detector,photo diode, or other components that can detect and measure opticalsignals on the fibers, and particularly measure the power level of thesignal.

Additionally, the monitors 208 and 210 may analyze the power level ofthe test portion of the optical signal received from the filter 202and/or filter 204 to determine the validity of the overall opticalsignal. Typically, optical signals are transmitted at differentwavelengths with differing power level outputs. The power level of anoptical signal is generally based on the signaling source used toprovide the optical signal. For example, high-power lasers may be usedto drive optical signals at correspondingly high power levels. Over timethe power level of the signaling source (e.g. the laser) can decrease,causing the optical signal power output to decrease. The monitors 208and 210 may measure the power level of the test portion of the opticalsignal and compare it to a power level threshold stored in themonitoring device, to determine whether the original optical signal isvalid. When the power level of the test portion of the optical signal isbelow an acceptable power level threshold, the optical signal isconsidered invalid. In contrast, when the measured power level of thetest portion of the optical signal is above the power level threshold,the optical signal is considered valid. For example, the monitoringdevice may have an established power level threshold range indicatingthat an optical signal with a power level above 0 dBm (1 milliWatt) isconsidered valid and an optical signal with a power level below −50 dBmis considered invalid. Thus, if the optical test device 104 measures thepower level of the test portion of the optical signal at 1 dBm orgreater, the optical test device 104 will provide an indication that theoptical signal, as well as the entirety of the optical fiber and/oroptical connection, is valid.

Besides identifying a fiber with a low or no signal, the optical testdevice 104 may also help identify overly high power level of the testportion of the optical signal. Being able to identify optical signalswith power output levels that are too high is important, as high powerlevels may cause problems such as over saturation of optical receivers.Thus, in such an implementation, the optical test device, andparticularly the monitor, may include an upper threshold that whenexceeded causes an error indication. Abnormally high power levels may becaused when a laser's launch power is too high or a higher power laserthan specified is deployed for a given length of fiber, which can bothover saturate the optical receivers at the customer equipment.

In one possible implementation, the optical test device includes one ormore light emitting diodes (LED(s)), or other forms of visual indicationtied to the signal strength and/or the threshold values. For example, ifa valid signal exists, the monitors 208 and 210 may illuminate one ormore of the LED(s), 216, 218, 220 operatively coupled to the opticaltest device 104. Hence, for example, when the signal strength is greaterthan 1 milliWatt a green light may be illuminated and should the signalfall below 1 milliWatt (e.g. below −50 dBm) a red light is illuminated.

In yet another example, the monitors 208 and 210 may identify theoptical signal as strong, average or weak, and subsequently illuminatethe one or more LEDs 216, 218, 220 operatively coupled to the opticaltest device 104. In such an implementation, the proper operating rangeof the optical signal may be defined, with visual indicators illuminatedwhen the test portion of the optical signal falls within a predefinedportion of the range. For example, if the proper operating range is 1dBM to 9 dBM, the device may be configured with thresholds correspondingto ranges falling between 1 and 3 dBM (weak), 4 and 6 dBM (average), and7 and 9 dBM (strong). Thus, when the optical signal is measured asfalling within one of the predefined ranges a corresponding indicationis provided. While the device is discussed as having LEDs, it is alsopossible to include a single multi-color LED, other lighting types, or aliquid crystal display, which may provide more detailed informationincluding the actual measured power level. Other mechanisms that arecapable of conveying information on the monitoring and/or test statuscan also be implemented or information can be transmitted to a remote orcentralized location for further processing.

According to another aspect of the current disclosure, the monitors 208and 210 may process the portion of the optical signal from the filter202 or filter 204 to detect a signal indicating that the optical testdevice 104 should trigger the switches 212 and 214 to change from apass-through state to a loop-back state. For example, when a connectionissue is identified by the monitor (e.g. a power level falling below apower threshold), a signal may be transmitted to the test device toenter the loop-back state. For example, the monitor 208 may detect asignal encoded within the optical signal received over the Tx fiber 106.The encoded signal may originate from the device shown in FIG. 4A(discussed herein) or may originate from any number of conventionalnetwork components suitable to generate a digital or an optical signal.

In one aspect, the encoded signal may be a digital sequence, such as apredetermined series of bits represented by a series of digital zeros(“000000”) and/or a series of digital ones (“111111”) for apredetermined amount of time, such as a three seconds. The encodedsignal may also include header and tail information as necessary totransmit the encoded signal through the network. Other types of encodedsignals may also be detected. In one implementation, an encoded signalis transmitted on one or more of the fibers connected with the opticaltest device 104 and the monitor 208 is configured to identify theencoded signal. For example, the monitor 208 may be programmed with orotherwise include a reference signal, and be capable of detecting amatch. When the encoded signal is identified, the optical test device104 will automatically change to a loop-back state and begin looping anyoptical signals sent from the network service device 102 back to thenetwork service device 102 allowing additional testing and monitoring ofthe optical link connected with the test device without additionalequipment installed at the customer's location.

The optical test device enters the loop-back state when the monitors 208and 210 detect a signal encoded within the optical signal or the deviceotherwise is commanded to enter the loop-back state, which directs theswitches 211 and 214 to be toggled. The switches 212 and 214 are toggledfrom a first position, which corresponds to a normal state in which anyoptical signal sent over the Tx fiber 106 simply passes through theoptical test device 104 to the customer device 108, to a secondposition, where any optical signals sent over the Tx fiber 106 loop-backthrough the optical test device 104 to the optical network serviceprovider device 102 by way of the Rx fiber 109. Thus, after the opticaldevice 104 is placed in a loop-back state, an optical signal sent overthe Tx fiber 106 will pass from the filter 204 to the switch 210, downthe optical loop-back path 107, to the switch 212 and pass over the Rxfiber 109A back towards the network service provider device 102. Theswitches 212 and 214 may be mechanical switches, electronic switches,such as relays, optical switches, and/or any other type of switch. Oncethe optical test device 104 is in a loop-back state, various tests, suchas high-level tests, packet-level tests, and light-level tests may beconducted to determine the health and status of the optical signaland/or optical services being provided.

Besides entering a loop-back state in response to an encoded signal, thedevice may also be configured with a manual switch 222 or switches tochange between a pass through state/normal state and a loop-back state.Various possible implementations may be configured to enter a loop-backstate in response to an encoded signal, a signal from a manual switch orswitches, as well as other possible means.

The optical test device 104 may be returned to its normal, non-test,operational pass-through state when testing and monitoring of anyoptical signals and/or optical services provided by the network serviceprovider is complete. In addition, the optical test device 104 may beconfigured to return to the pass through state in case of its failure.For example, should the optical device 104 lose power, the switches 212and 214 will return to the pass-through position and/or closed state.

FIG. 3 illustrates an example of an optical communication network 300that includes a provider optical test device 310 that may be used tocontrol or otherwise communicate with the optical test device 304. Theprovider optical test device may be configured to monitor signalstrength on fibers connected to it, as well as enter a loop-back statefor additional testing. Similarly to the systems discussed withreference to FIG. 1 and FIG. 2, in a pass through configuration, boththe provider test device 310 and the optical test device 304 allow datasignals on fibers 106 and 109 to pass unimpeded to and from the networkprovider device 302 and the customer device 308.

Thus, in one configuration of the provider optical test device 310, thetransmit and receive fibers 106A and 109A are connected directly totransmit and receive fibers 106B and 109B such that opticaltransmissions proceed uninterrupted from the network service providerdevice 302 to the customer device 308. The provider optical test device310, however, can be configured to control when optical signals passthrough from the network service provider device 302 to the customerdevice 308 or when the device activates the optical test device 304 tomonitor and test the optical fiber links. For example, the provideroptical test device 310 may be configured to initiate an encoded signalon the transmission fiber 106A to cause the optical device 304 to changeto a loop-back state, during which the optical device 304 loops anyoptical signal originating from the network service provider device 302back to the network service provider device 302, allowing testing andmonitoring of the fiber connected from the network service providerdevice 302 to the customer device 308.

FIGS. 4A and 4B are block diagrams illustrating two possibleimplementations of the provider optical test device 310. The componentsof the provider test device 310 may be used to change the state of theprovider optical test device 310 from a default pass through state to aloop-back state, which allows a network service provider to conducttests of optical fibers, and/or optical links. The provider optical testdevice 310 may include components similar to those in the optical testdevice 304 that may be used in conjunction with other components, suchan optical switch 414 and a test laser 416 to change the state of theprovider test device. For example, in one embodiment, the provideroptical test device 310 includes filters 404 and 406, and monitors 408and 410 that operate similarly to the filters 202 and 204, and themonitors 208 and monitor 210 respectively, of the optical test device104 described above in connection with FIGS. 1 and 2. These filters andmonitors may be used in conjunction with other components in theprovider optical test device 310 to change the provider optical testdevice 310 from a pass-through state to a loop-back state.

The provider optical test device 310 may include a test laser 416 thatprovides an encoded signal on the transmission fiber 106 B to cause thecustomer test device to enter the loop-back state. The encoded signalfrom the test laser 416 is coupled to the transmission fiber through anoptical switch 414. Optical switches enable signals in optical fibersand/or optical circuits to be selectively switched from one circuit orfiber to another.

The provider optical test device may also include a control interface412 that provides control over the laser to initiate the encoded signaland operate the optical switch, as well as performs other operations,including running or facilitating different tests. The control interface412 may be a hardware interface configured to exchange information witha variety of computing devices, such as a processing device, networkdevices, etc. The control interface may be accessed through various wayssuch as through a graphical user interface (GUI) or may be operated atthe machine level such as through a machine-to-machine commandinterface, through a command and control protocol, or otherwise. Thus,any of a variety of computing, networking, and/or telecommunicationdevices may be configured to exchange information with the controlinterface 412. Alternatively, in various implementations, the controlinterface 412 may be implemented as instructions, modules, a softwareapplication, and/or a software interface located within the provideroptical test device 310 or on an external processing device, such as acomputer, a communication device, a server computer, a tablet computer,a mobile processing device, a mobile communication device and/or thelike, that includes one or more processors to process software or othermachine-readable instructions, a memory to store the software or othermachine-readable instructions and data, and a communication system tocommunicate with the optical test device 104 through a wireline and/orwireless communications, such as through the Internet, an intranet, andEthernet network, a wireline network, a wireless network, and/or anothercommunication network. Such processing devices may further include adisplay (not shown) for viewing data, such as a computer monitor, and aninput device (not shown), such as a keyboard or a pointing device (e.g.,a mouse, trackball, pen, touch pad, or other device) for entering dataand navigating through data, including exams, images, documents,structured data, unstructured data, HTML pages, other web pages, andother data.

According to another aspect of the current disclosure, the controlinterface 412 may include a test suite 418. The test suite 418represents instructions or modules capable of performing particulartesting tasks or implementing particular abstract data types. In oneaspect, the test suite 418 may be used in conjunction with the testlaser 416 to send signals to the optical test device 104. For example,the test suite 418 may work in conjunction with the control interface412 to cause the test data pattern to be transmitted by the test laser416 on the transmission fiber. Further, the test suite may provide acomparison pattern to the monitors 408 and/or 410 so that the monitorscan compare the test pattern as received with the comparison pattern andthereby identify the integrity of the signal at the various possiblemonitoring locations as well as isolate potential problems along thepath whether in a loop-back configuration or not. Further, the monitoror monitors may convey the detected test pattern to the test suite 418for monitoring and/or analysis to identify faults, disconnections, fibercontinuity, and accuracy of transmission.

While FIG. 4 includes a single optical switch and a test laser, it iscontemplated that the provider optical test device 310 may beimplemented using multiple test lasers and optical switches inconjunction with ports to support multiple customers. Moreover, theoptical test device may further include or otherwise connect the testlaser with the receive fiber 109 as well as any other fibers connectedwith the provider test device. Additionally, in one possibleimplementation as shown in FIG. 4B, the provider optical test device mayonly include the control interface 412, the test laser 416, and theoptical switch 414.

FIG. 5 is a flow chart illustrating an example of a method formonitoring optical signals and services on an optical network. To begin,at operation 502, an optical signal is received at a test device. Forexample, an optical signal is transmitted over Tx fiber 106 and receivedby the optical test device 104. A portion of the optical signal isreceived to test the optical signal at 504. For example, the opticalsignal received at the optical test device 104 may be filtered by thefilter 202 resulting in a portion of the optical signal beingtransmitted to the monitor 208 for testing, such as testing the powerlevel of the portion of the optical signal. When the power level isabove a certain threshold the optical signal is valid. At 506, the testdevice is switched from a first state to a second state when a signal isdetected. For example, an encoded signal represented by a predefinedseries of bits may be detected by the monitor 208 indicating that theoptical test device 104 should change from a pass-through state to aloop-back state. Accordingly, the monitor 208 causes the switches 210and 212 in the optical test device 104 to be toggled from first positionresulting in a pass-through state to second positions resulting aloop-back state. While in the loop-back state, the optical test device104 loops any optical signals originating from the network serviceprovider device 102 for transmission to the customer device 108, back tothe network service provider device 102. Once in a loop-back state thenetwork provider may perform various tests to on optical signal sent tothe optical test device 104, or any optical fibers connected to theoptical test device 104.

FIG. 7 is another alternative embodiment of an optical test device 700.The various features discussed and shown in FIG. 7 may be used inconjunction with various other embodiments discussed herein andsimilarly features discussed in other embodiments may be used inconjunction with features discussed with reference to FIG. 7. The deviceof FIG. 7 employs a dedicated test subchannel (T_(s)) with a test signalcarried on a fiber 702 between a first device 706 and the optical testdevice 700. The test signal may be a particular wavelength differentfrom wavelengths (or channels) carrying data. So, for example, if theoptical fiber can carry 40 wavelengths (channels) of data, then some orall of one particular channel is used for testing the transmit and/orreceive fibers (waveguides) between the first device, which may be anetwork service provider device or a gateway, and a second device 708,which may be customer device or otherwise between two devices. Further,the test device 700 does not include switches to create the loop-backpath like some of the other embodiments discussed herein. Rather, anoptical filter 710 is provided in the transmission path and the filterseparates the test subchannel (T_(s)) from the data channels. A couplingelement 712 in the return path adds the subchannel signal to the datachannels for return to the originating device (e.g., the networkprovider device) using a return fiber 704.

A monitor 714 or other testing component is placed in the subchannelpath, which may be between the filter 710 and coupling element 712. Themonitor may be configured to test and report various characteristics ofthe subchannel signal, such as power, attenuation and the like. Further,the monitor may automatically report the test data by way of a networkconnection 718. Alternatively or in addition, the monitor may beconfigured to receive a query or other request from a user through aconnection 718 to the monitor, and return the test data to the user. Inone example, the subchannel signal (T_(s)) is returned to the networkprovider device and may be tested and/or monitored a second time at thenetwork provider. Thus, the optical test device may be used to detectand report signal and connection issues in the transmission path to thecustomer equipment. Also, by adding the test signal back into thereceive line, the return path from the customer equipment to the networkequipment may also be tested. In this embodiment, the test signal canalways be present and is separate from the data channels so a switchthat causes loop back testing is not used.

The monitor may also embed test data into the test channel rather thanor in addition to providing a separate mechanism to query or obtain testresults from the monitor. Thus, after the monitor analyzes the testsignal (T_(s)), the results of the analysis are included in the testsignal as T_(s)′. At the network service provider such as by using aprovider test device as shown in FIG. 5A, the test information may beextracted from the test channel by monitor 410. Additionally, themonitor 410 may also separately test the integrity of the test signal todetermine if there are any issues in the Rx Fiber between the customerequipment and the network provider equipment.

FIG. 8 illustrates another alternative implementation of an optical testdevice 800 operating in a testing system taking advantage of the deviceand including some monitoring features at a first device 812, which maybe a service provider device such as a gateway. More particularly, anoptical test device 800 is coupled between a transmission fiber 802,which originates at the first device, and a second device 810, which maybe a customer device. Data signals on the transmission fiber areconfigured to pass through a filter 804 to the customer device. Thus,the transmission fiber 802 may pass through the optical test device tothe customer device or the transmission fiber 802(A) may be opticallyconnected to the optical test device and a second transmission fiber802(B) connected between the test device and the customer device.Similarly, a receive fiber or fibers 802(A), (B) provide a return datapath from the second device (e.g., customer equipment) 810 through theoptical test device and to the first device (e.g., network providerequipment). The transmission fiber, similarly to the embodimentdiscussed with regard to FIG. 7, includes a test subchannel (T_(s)) thatmay occupy some or all of one of the wavelengths carried on the fiber.The filter 804 extracts the subchannel and the signal carried thereon(T_(s)) and loops it back to the provider device by way of a secondfilter 806 and the return fiber 804(A).

In this embodiment, monitoring of the subchannel and any test signalthereon, is performed at the first device. A test signal maycontinuously or intermittently occupy one or more transmission fibersfrom the first device or the test signal may be optically coupled to thetransmission fiber at an optical coupling element 814. In the lattercase, the test signal is generated and switched on the transmissionfiber by way of a switch 818 that receives the test signal from a probe820. The probe may also include similar features and/or functions asshown in FIG. 5A and discussed relative to elements 412, 418 and/or 416.

The switch and probe may also receive and monitor the test signalreturning on the receive fiber 804(A). In this example, a filterextracts the test signal and provides the signal to the probe 820. Theswitch allows the system to receive and test signals from one or manyreturn fibers connected with the first device 812. Thus, for example,optical test devices 800N may be connected to various customer devicesand provide a test signal loop back path to and from a gateway. Theswitch 818, at the gateway, is connected with a plurality of filters 816and 818 (N) receiving test signals from a corresponding plurality oftest devices. The switch, which may be a multiplexor, is configured,such as with a select line, to couple the test signal Ts(N) from aselected receive fiber 804(N) to the probe 820 to test the transmissionand/or receive fibers and/or the signal quality thereon.

Thus, embodiments, in accordance with aspects of the present disclosure,an optical test device is used to test and monitor optical signals andoptical network services provided by an optical network service providerwithout having to install expensive physical equipment at customer'sremote location.

The description above includes example systems, methods, techniques,instruction sequences, and/or computer program products that embodytechniques of the present disclosure. However, it is understood that thedescribed disclosure may be practiced without these specific details.

In the present disclosure, the methods disclosed may be implemented assets of instructions or software readable by a device. Further, it isunderstood that the specific order or hierarchy of steps in the methodsdisclosed are instances of example approaches. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the method can be rearranged while remaining within thedisclosed subject matter. The accompanying method claims presentelements of the various steps in a sample order, and are not necessarilymeant to be limited to the specific order or hierarchy presented.

The described disclosure may be provided as a computer program product,or software, that may include a machine-readable medium having storedthereon instructions, which may be used to program a computer system (orother electronic devices) to perform a process according to the presentdisclosure. A machine-readable medium includes any mechanism for storinginformation in a form (e.g., software, processing application) readableby a machine (e.g., a computer). The machine-readable medium mayinclude, but is not limited to, magnetic storage medium (e.g., floppydiskette), optical storage medium (e.g., CD-ROM); magneto-opticalstorage medium, read only memory (ROM); random access memory (RAM);erasable programmable memory (e.g., EPROM and EEPROM); flash memory; orother types of medium suitable for storing electronic instructions.

It is believed that the present disclosure and many of its attendantadvantages will be understood by the foregoing description, and it willbe apparent that various changes may be made in the form, constructionand arrangement of the components without departing from the disclosedsubject matter or without sacrificing all of its material advantages.The form described is merely explanatory, and it is the intention of thefollowing claims to encompass and include such changes.

While the present disclosure has been described with reference tovarious embodiments, it will be understood that these embodiments areillustrative and that the scope of the disclosure is not limited tothem. Many variations, modifications, additions, and improvements arepossible. More generally, embodiments in accordance with the presentdisclosure have been described in the context of particularimplementations. Functionality may be separated or combined in blocksdifferently in various embodiments of the disclosure or described withdifferent terminology. These and other variations, modifications,additions, and improvements may fall within the scope of the disclosureas defined in the claims that follow.

What is claimed is:
 1. A method comprising: receiving an optical signalat an optical test device, the optical test device comprising at leastone monitoring device and a first switch; receiving, at the monitoringdevice, a portion of the optical signal to detect a control signalwithin the optical signal, the control signal used to control the statusof the optical test device, wherein detection of the control signalincludes detecting a power level of the portion of the optical signaland comparing the detected power level of the portion of the opticalsignal with a threshold power level to determine if the signal is valid;and altering the state of the optical test device from a first state toa second state when the control signal is detected at the optical testdevice.
 2. The method of claim 1, wherein altering the state of theoptical test device comprises toggling the first switch from a firstposition to a second position to alter the state of the optical testdevice from the first state to the second state when the control signalis detected.
 3. The method of claim 2, wherein the control signal is anencoded signal in the optical signal.
 4. The method of claim 3, whereinthe encoded signal is a predetermined series of bits.
 5. The method ofclaim 2, further comprising altering the state of the optical testdevice to a pass-through state when the optical test device fails. 6.The method of claim 2, wherein the first state is a pass-through stateand the second state is a loop-back state.
 7. A method of testing anoptical connection between devices comprising: receiving, at a remotedevice, a test signal on a particular wavelength of a plurality ofwavelengths carried by a first optical fiber; returning the test signalon a second optical fiber, the test signal returned on the particularwavelength; providing for determining a characteristic of at least thefirst optical fiber or the second optical fiber at a second device atthe remote device, obtaining at least one characteristic of at least thefirst optical fiber from the test signal; and creating a data signalrepresentative of the at least one characteristic and transmitting thedata signal on the second optical fiber.
 8. The method of claim 7further comprising: at the second device, receiving the test signal onthe second optical fiber; and determining at least one characteristic ofat least one of the first optical fiber or the second optical fiber.